Erin Andrews, who signed an endorsement deal with Reebok last month, is not the only ESPN personality or member of its “College GameDay” team to have a contract with a major shoe company.

Chris Fowler, Kirk Herbstreit and Lee Corso have deals with Nike that Corso described as a joint arrangement that largely involves speaking engagements for the athletic shoe and apparel company.

After an inquiry to ESPN about the announcers’ Nike contracts, Josh Krulewitz, an ESPN spokesman, said that Fowler, the host of “GameDay,” is “ending his minor association” with Nike “to avoid any potential perception issues.” Fowler was not made available for an interview.

In defending the announcers, Krulewitz said: “By any objective measure, Chris, Kirk and Lee’s on-air work is unassailable. Their content has not been compromised by this relationship.”

Corso, Fowler and Herbstreit’s deals with Nike were never announced or disclosed to viewers. “We were unaware of these deals,” Krulewitz said.

By comparison, Andrews’s deal to endorse Reebok’s ZigTech brand was announced in a news release from the shoe company, which is owned by Adidas.

“College GameDay” won Sports Emmy awards for outstanding weekly studio show in 2008 and 2010 and is a major weekly showcase for college football. Fowler, Corso and Herbstreit, who also calls Saturday night games for ABC, are three of the sport’s best-known personalities; tens of thousands of fans surround them, as well as Andrews and the analyst Desmond Howard, on their set at a different campus each week.

ESPN and Nike are major forces in college sports. ESPN has numerous contracts to carry games and Nike has sponsorship agreements with dozens of universities, to which it supplies shoes and apparel. So it is not a surprise that Nike has aligned itself with announcers from a marquee program like “GameDay.”

Derek Kent, a Nike spokesman, confirmed the deals with Fowler, Corso and Herbstreit.

“While we don’t disclose the specific nature of our contracts,” Kent said, “they have appeared as M.C.’s at various Nike events in the past.”

Corso said his obligations to Nike were not burdensome and did not compromise his work.

“We don’t do very much and they’re unbelievable to us,” Corso said Monday by telephone. “We wear their product, which is part of it.” But he said they were not obligated to tell viewers about the Nike connection. “I might have Nike shoes on, but it’s got nothing to do with ‘College GameDay.’ ”

Still, Nike’s tie to the “GameDay” announcers creates potential conflicts of interest, said Bob Steele, the director of the Prindle Institute for Ethics and a journalism professor at DePauw University. “It’s not just what’s said or written but what stories are covered and the frame for the story,” he said. “It’s the questions that are asked and not asked in an interview, and who gets interviewed.”

He added, “You do have to wonder why a sports journalist, or any journalist, would wander in this kind of ethical minefield without recognizing the consequences.”

ESPN said that it allowed reporters and personalities to sign endorsement deals on a case-by-case basis. Krulewitz said that for former players like Herbstreit and former coaches like Corso, “it’s common for them to have endorsement deals” after they become analysts.

ESPN approved Andrews’s deal with Reebok while saying it would inform the audience if a conflict arises between her commercial and reporting roles. But last year, Jenn Brown, a college sports reporter for ESPN, was prohibited from being in a MillerCoors ad for Icehouse beer.

James Andrew Miller, the co-author, with Tom Shales, of the forthcoming book “Those Guys Have All the Fun: Inside the World of ESPN,” said that the network needed a consistent policy about which deals represent potential conflicts of interest and which do not.

But he said: “ESPN is not well served when it says it doesn’t know what its employees are doing. That’s a little troubling. It suggests that a policy to address conflicts is not in effect or there isn’t an effective means of communicating with them about it.”

Sportscasters have been in commercials since the early days of television. They are viewed as effective communicators if not outright entertainers; the current ranks of sportscasters who also endorse products include CBS’s Jim Nantz and Nick Faldo; ESPN’s Chris Berman; Fox’s Howie Long and Troy Aikman; NBC’s Johnny Miller; TNT’s Charles Barkley; and retired announcers like John Madden and Keith Jackson.

In 2005, when Suzy Kolber, an ESPN reporter, was appearing in television ads for Chevrolet, ESPN’s ombudsman, George Solomon, wrote that she “does an excellent job” at both tasks, but “I just wish she would choose one of the two jobs.” He concluded by writing, “ESPN would be better served not permitting its on-air personnel to go outside the compound and do commercials.”

A version of this article appears in print on February 15, 2011, on page B11 of the New York edition with the headline: Several ESPN Broadcasters Have Had Shoe Contracts. Order Reprints|Today's Paper|Subscribe